Polymer compound for photoresist

Abstract

A polymer compound for photoresists contains alkali-soluble groups being protected by protecting groups capable of leaving with an acid, and is thereby insoluble or sparingly soluble in an alkaline developer, in which part or all of the protecting groups are multifunctional protecting groups each protecting two or more alkali-soluble groups. The alkali-soluble groups may be phenolic hydroxyl groups. The polymer compound may correspond to a polyol compound having an aliphatic group and an aromatic group bound to each other alternately, the aromatic group having an aromatic ring and two or more hydroxyl groups bound to the aromatic ring, except with phenolic hydroxyl groups of the polyol compound being protected by protecting groups capable of leaving with an acid. The polymer compound for photoresists can give a resist film with less line edge roughness (LER), while exhibiting excellent workability and resolution.

1 . A polymer compound for photoresists, the polymer compound comprising alkali-soluble groups being protected by protecting groups capable of leaving with an acid, and the polymer compound being insoluble or sparingly soluble in an alkaline developer, wherein part or all of the protecting groups are multifunctional protecting groups each protecting two or more alkali-soluble groups. 
     
     
         2 . The polymer compound for photoresists according to  claim 1 , wherein the alkali-soluble groups are phenolic hydroxyl groups. 
     
     
         3 . The polymer compound for photoresists according to  claim 1  or  2 , the polymer compound for photoresists being a polyol compound having at least one aliphatic group and at least one aromatic group bound to each other alternately, the aromatic group having at least one aromatic ring and two or more phenolic hydroxyl groups bound to the aromatic ring, the phenolic hydroxyl groups in the polyol compound protected by protecting groups capable of leaving with an acid. 
     
     
         4 . The polymer compound for photoresists according to  claim 3 , wherein the polyol compound is a product of an acid-catalyzed reaction between an aliphatic polyol and an aromatic polyol. 
     
     
         5 . The polymer compound for photoresists according to  claim 4 , wherein the acid-catalyzed reaction is a FriedelCrafts reaction. 
     
     
         6 . The polymer compound for photoresists according to  claim 4 , wherein the aliphatic polyol is an alicyclic polyol. 
     
     
         7 . The polymer compound for photoresists according to claim, wherein the aliphatic polyol is an adamantanepolyol having an adamantane ring and two or more hydroxyl groups bound at the tertiary positions of the adamantane ring. 
     
     
         8 . The polymer compound for photoresists according to  claim 4 , wherein the aromatic polyol is hydroquinone. 
     
     
         9 . The polymer compound for photoresists according to  claim 4 , wherein the aromatic polyol is a naphthalenepolyol. 
     
     
         10 . The polymer compound for photoresists according to  claim 1 , wherein the polymer compound for photoresists before the protection of the alkali-soluble groups by the protecting groups capable of leaving with an acid has a weight-average molecular weight of 500 to 5000. 
     
     
         11 . The polymer compound for photoresists according to  claim 1 , wherein an acetal group is formed as a result of the protection of the alkali-soluble group by the protecting group capable of leaving with an acid. 
     
     
         12 . The polymer compound for photoresists according to  claim 11 , wherein the acetal structure is formed through a reaction between a phenolic hydroxyl group and a vinyl ether compound. 
     
     
         13 . A photoresist composition comprising at leas the polymer compound for photoresists according to  claim 1 . 
     
     
         14 . A process for the formation of a resist pattern, the process comprising the steps of forming a resist film from the photoresist composition according to  claim 13 ; patternwise exposing the resist film; and developing the pattern-wise-exposed resist film.